Drills are typically used by tradesmen and home handymen to perform a multitude of various tasks. The most common task is generally the drilling of holes into various materials. Drill bits are designed such that they are very effective in this process whereby the rapid rotation of the bit effectively cuts away at the work piece thereby forming an aperture. These drill bits, which are typically locked within a mandrel are effective for apertures of a small diameter, however, it is often required that much larger apertures be drilled.
This is where the invention of the hole saw came into being which incorporates a cylindrically shaped member including cutting teeth on one end and a threaded bore on the other. This threaded bore engages with an oppositely threaded member connected to the mandrel commonly referred to as a boss. The drill bit is incorporated into the hole saw assembly and protrudes through the boss a distance greater than that of the hole saw member so that it can be used to align the drill with the centre of the circle being cut. That is, when using a hole saw member to drill a hole into a work piece, it is much easier to align a pilot drill with a centre point of a circle than it is to align the cutting teeth of a hole saw member with the perimeter of a circle. The pilot drill forms an initial hole in the work piece until the hole saw teeth reach the material surface where they then proceed to accurately drill the required hole.
Although this has proven to be an effective method of drilling larger holes, it becomes apparent that when faced with having to increase the diameter of an existing hole, there exists no centre-point to which a pilot drill may be aligned. This provides a problem because as mentioned, it is very difficult to accurately drill a large-diameter hole without some type of centre alignment. In many situations, the handyman is forced to manually hand-work the work piece so that enlargement can be achieved.
It is an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.
Insofar as the applicant is aware, there exists no hole saw boss including a threaded member adapted to accommodate two hole saws of the same or different diameter threaded bore.